Electromagnetic Slide-Open Detergent Dispenser for Dishwashers

The problem

Built-in dishwashers need a compartment to hold detergent until the moment in the wash cycle when it should dissolve. Traditional dispensers often rely on wax motors or bi-metallic strips that expand under heat to pop a lid open. Over time, these thermal actuators lose their stroke, stick due to dried detergent residue, or respond slowly, causing the detergent to dump early or not at all.

The solution

The patent describes a dispenser built from a bottom shell and a front cover that snap together. Inside, a sliding cover rides over the washing-liquid cavity. Loading is handled manually: pressing a button moves a locking part against a pressure spring, separating it from the cover so a torsion spring (mounted in its own cavity between the cover’s upper wall plate and the cavity floor) slides the cover open. Once filled, the user pushes the cover closed and the lock re-engages.

For automatic release during the cycle, a pull-in electromagnet is provided. Its armature connects to a crank via a rotating shaft passing through pivot joint holes in the front cover and bottom shell. When the electromagnet is energized, the armature moves the crank, which pushes a driving part. This driving part carries a guide protrusion that slides along a guide groove, forcing the automatic locking component away from the sliding cover. Freed from the lock, the torsion spring drives the cover open, exposing the detergent to the wash water. A return spring (one end on the crank, the other anchored to the bottom shell) resets the crank when power is cut.

Who it is for

• Dishwasher OEMs and ODMs seeking an electromagnetically released detergent mechanism to replace wax-motor designs in new product lines.
• Appliance component suppliers that manufacture door-mounted modules and want to offer an electromagnetic alternative to thermal actuators.
• Commercial dishwasher builders looking for a release mechanism that does not depend on thermal expansion.
• Aftermarket repair brands looking for replacement dispensers that use solenoid-driven operation.

How it works

The main parts

Operating steps

1. Loading detergent - The user presses the button (6). This compresses the pressure spring (7) and pivots the locking part out of engagement with the sliding cover (3).
2. Cover opens - Released from the manual lock, the torsion spring (4) unwinds. One end pushes against the cover’s upper wall plate while the other pushes against the cavity floor, sliding the cover open along its track.
3. Filling and closing - Detergent is poured into the exposed cavity. The user pushes the sliding cover closed against the spring force until the locking part clicks back into place under pressure-spring tension.
4. Automatic release - During the wash cycle, current is supplied to the pull-in electromagnet (8). The armature (9) is drawn inward, pivoting the crank (10) around the rotating shaft (11).
5. Lock separation - The crank pushes the driving part (12). Its guide protrusion travels inside the guide groove, forcing the automatic locking component away from the sliding cover.
6. Dispensing - With the automatic lock cleared, the torsion spring slides the cover open, releasing the detergent into the tub.
7. Reset - Power to the electromagnet is cut. The return spring (14), stretched between the crank and the bottom shell, pulls the crank back to its resting position, ready for the next cycle.

Applications

Residential built-in dishwashers

Home appliances can use the electromagnet to release the detergent compartment. The solenoid operates without relying on thermal expansion.

Commercial under-counter machines

Restaurants run short, frequent cycles. An electromagnetic release avoids heat-soak issues associated with thermal actuators.

Drawer-style dishwashers

Compact drawer units have limited space behind the door panel. The profile of the sliding cover combined with the pull-in electromagnet fits into tighter cavities compared to bulky wax-motor housings.

Multi-compartment dispensers

Machines that separate pre-wash and main-wash detergent can use two independent electromagnetic modules on a single base shell. Each cavity opens on its own signal.

Retrofit and upgrade kits

Service technicians replacing failed wax-motor dispensers in older models can install this unit if the control board supports the required output. The mechanical footprint remains similar, but the release mechanism changes.

Where it is less suitable

• Portable countertop dishwashers that lack a dedicated driver circuit for an electromagnet may find the electrical integration more complex than a passive thermal latch.
• Extremely low-cost entry-level machines where the added expense of a coil, armature and crank mechanism outweighs the benefit.